Isoprothiolane: A Specialized Fungicide for Rice Disease Control

Technical Introduction

Isoprothiolane (chemical name: diisopropyl 1,3-dithiolan-2-ylidene-malonate) is a systemic fungicide mainly used in rice cultivation. It belongs to the dithiolane group of fungicides and is well-known for its high effectiveness against rice blast (Pyricularia oryzae / Magnaporthe grisea) and rice sheath blight (Rhizoctonia solani).

Its mode of action involves:

• Inhibiting melanin biosynthesis in fungal spores, preventing successful penetration of plant tissues.

• Interfering with fungal lipid metabolism, which weakens fungal growth and spore germination.

Isoprothiolane is absorbed by rice plants and translocated within tissues, providing preventive and curative action against fungal infection.

Applications

• Rice Cultivation:

  • Highly effective against rice blast (leaf blast, neck blast, and panicle blast).

  • Controls sheath blight, which is another major yield-reducing rice disease.

  • Sometimes used for seed treatment to protect seedlings from early-stage blast infection.

• Integrated Disease Management (IDM):

  • Often applied in rotation with tricyclazole, azoxystrobin, or propiconazole to delay resistance development.

• Other Crops (limited use):

  • In some countries, tested for activity against fungal pathogens in wheat, barley, and vegetables, but rice remains the primary crop.

Advantages

• Specialized Activity: Very effective against the two most destructive rice diseases (blast and sheath blight).

• Systemic Properties: Provides long-lasting protection by translocating inside the plant.

• Dual Action: Works as both a protective and curative fungicide.

• Seed Treatment & Foliar Spray: Flexible use depending on crop stage.

• Compatibility: Can be tank-mixed with other fungicides or insecticides for broader protection.

Specifications (Typical Parameters)

FAQ

Q1: What is Isoprothiolane mainly used for?
A: It is primarily used in rice farming to control blast disease and sheath blight, two of the most destructive fungal diseases in paddy cultivation.

Q2: How does it differ from Tricyclazole?

• Tricyclazole: A specific blast fungicide that blocks melanin biosynthesis.

• Isoprothiolane: Controls both blast and sheath blight, making it broader in scope.

Q3: Can Isoprothiolane be used as a seed treatment?
A: Yes, it is sometimes used to coat rice seeds before sowing, protecting seedlings against early infection by blast fungi.

Q4: Is resistance a problem with Isoprothiolane?
A: Resistance development has been reported in some regions, which is why it is recommended to use rotation or mixtures with other fungicides in Integrated Disease Management (IDM).

Q5: Is Isoprothiolane toxic to humans and the environment?
A: It has moderate toxicity (oral LD₅₀ in rats > 1,000 mg/kg), lower than many organophosphates, but safety precautions are still required. It is also toxic to fish and aquatic life, so runoff into waterways should be avoided.